when to stop treatment.

Any medical people who can help here.

Elderly father-in-law (85 last week)is in hospital with pneumonia. Had a vomiting bug a couple of days ago and inhaled some vomit (according to X-rays). The doctor at A&E asked if he had an advanced care directive and did we want to withhold antibiotics. His wishes of 3 years ago was for no heroic measures or unnecessary interventions if he had reached the end of his life.

He is currently receiving oral antibiotics, saline drip and oxygen as he was having trouble breathing and speaking(slurring words) when we took him into hospital yesterday.

He has alzheimers (knows family members, can't remember things from one minute to the next, still reads The Australian, does the crosswords and suduko). He also has slow growing prostate cancer and a small tumour in the lung from the original cancer.

My question is whether this condition will be terminal or can antibiotics resolve the problem and in that case should he be on IV antibiotics. No one seems able to spell out the likely outcome and we don't know the best course of action.

Up until now he has been cared for at home and has been happy to sit in his chair on the verandah looking out over the farm and taking part in the activities mentioned above. Is this a fight worth taking on?

Any insights would be helpful.